Apparatus for inspecting droplet and method for inspecting droplet using the same

This application claims priority to Korean Patent Application No. 10-2023-0101230, filed on Aug. 2, 2023, and all the benefits accruing therefrom under 35 U.S.C. § 119, the content of which in its entirety is herein incorporated by reference.

The disclosure relates generally to an apparatus for inspecting droplet. More particularly, the disclosure relates to an apparatus for inspecting droplet and a method for inspecting droplet using the same.

A printing apparatus including an inkjet head is used to form an alignment layer or apply ultra-violet (“UV”) ink on a substrate in a process of manufacturing a liquid crystal display device, or to apply ink to a substrate in a process of manufacturing an organic light-emitting display device.

In the process using the inkjet head, an inspection apparatus may be used to inspect the amount of a droplet discharged from each of a plurality of nozzles included in the inkjet head and whether or not the droplet is discharged.

Embodiments provide a droplet inspection apparatus that inspects droplet discharge defects.

Embodiments provide a droplet inspection method for inspecting droplet discharge defects.

An apparatus for inspecting a droplet among a plurality of droplets in an embodiment of the disclosure includes an inspection substrate defining a penetrating area corresponding to a nozzle portion that discharges the plurality of droplets, the penetrating area through which at least some of the plurality of droplets, which are discharged from the nozzle portion, pass and a camera that measures the droplet disposed on one surface of the inspection substrate without passing the inspection substrate through the penetrating area.

In an embodiment, the plurality of droplets discharged from the nozzle portion may include a main droplet and a satellite droplet. A volume of the satellite droplet may be smaller than a volume of the main droplet.

In an embodiment, the camera may measure the satellite droplet disposed on the one surface of the inspection substrate.

In an embodiment, the nozzle portion may include a plurality of nozzles arranged in a line along a first direction in a plan view, and the penetrating area may define a plurality of penetrating holes respectively corresponding to the plurality of nozzles. A first interval between the plurality of penetrating holes in the first direction may be an integer multiple of a second interval between the plurality of nozzles in the first direction.

In an embodiment, the plurality of penetrating holes may correspond one-to-one with the plurality of nozzles.

In an embodiment, the plurality of penetrating holes may include a plurality of groups arranged in the line along the first direction in the plan view. The plurality of groups may be arranged along a second direction crossing the first direction.

In an embodiment, the plurality of penetrating holes may be arranged in a zigzag shape in the plan view.

In an embodiment, a maximum length of each of the plurality of penetrating holes in the first direction may be smaller than the second interval between the plurality of nozzles in the first direction.

In an embodiment, the inspection substrate may include a liquid-repellent material.

In an embodiment, the apparatus may further include a receiving portion positioned under the inspection substrate and that accommodates a droplet, among the plurality of droplets, passing the inspection substrate through the penetrating area.

A method for inspecting a droplet among a plurality of droplets in an embodiment of the disclosure includes preparing an inspection substrate defining a penetrating area through which at least some of the plurality of droplets, which are discharged from a nozzle portion, pass, aligning the inspection substrate so that the penetrating area corresponds to the nozzle portion, discharging the plurality of droplets from the nozzle portion, and measuring the droplet disposed on one surface of the inspection substrate without passing the inspection substrate through the penetrating area.

In an embodiment, the plurality of droplets discharged from the nozzle portion may include a main droplet and a satellite droplet. A volume of the satellite droplet may be smaller than a volume of the main droplet. The main droplet may be discharged before the satellite droplet.

In an embodiment, the main droplet may pass the inspection substrate through the penetrating area. A portion of the satellite droplet may be disposed on the one surface of the inspection substrate without passing through the inspection substrate.

In an embodiment, in the measuring the droplet on the one surface of the inspection substrate, the portion of the satellite droplet may be measured.

In an embodiment, the method may further include changing discharge conditions of the nozzle portion by evaluating information about the droplet disposed on the one surface of the inspection substrate after the measuring the droplet.

In an embodiment, the nozzle portion may include a plurality of nozzles arranged in a line along a first direction in a plan view. The penetrating area may define a plurality of penetrating holes. The plurality of penetrating holes may be aligned to respectively correspond to the plurality of nozzles in the aligning the inspection substrate.

In an embodiment, a first interval between the plurality of penetrating holes in the first direction may be an integer multiple of a second interval between the plurality of nozzles in the first direction.

In an embodiment, a maximum length of each of the plurality of penetrating holes in the first direction may be smaller than the second interval between the plurality of nozzles in the first direction.

In an embodiment, in the aligning the inspection substrate, the inspection substrate is aligned so that the plurality of penetrating holes correspond one-to-one with the plurality of nozzles.

In an embodiment, the nozzle portion may move along a second direction crossing the first direction.

A droplet inspection apparatus in an embodiment of the disclosure may include an inspection substrate defining a plurality of penetrating holes through which at least some of a plurality of droplets, which are discharged from each of a plurality of nozzles, pass and a camera that measures a droplet disposed on one surface of the inspection substrate. In this case, the droplet disposed on the one surface of the inspection substrate may be a satellite droplet that is not discharged to a target position.

By defining the penetrating holes through which at least some of the droplets pass the inspection substrate, each of the nozzles may discharge hundreds of thousands to millions of the droplets while the position of an inkjet head is fixed. The camera may measure the satellite droplet disposed on the one surface of the inspection substrate.

Accordingly, the droplet inspection apparatus may inspect discharge defects of the satellite droplet, where the occurrence frequency of the discharge defects is relatively low. In other words, the droplet inspection apparatus may simplify a process for inspecting discharge defects of the satellite droplet.

Hereinafter, embodiments of the disclosure will be described in detail with reference to the accompanying drawings. The same reference numerals are used for the same components in the drawings, and redundant descriptions of the same components will be omitted.

It will be understood that when an element is referred to as being “on” another element, it can be directly on the other element or intervening elements may be present therebetween. In contrast, when an element is referred to as being “directly on” another element, there are no intervening elements present.

It will be understood that, although the terms “first,” “second,” “third” etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, “a first element,” “component,” “region,” “layer” or “section” discussed below could be termed a second element, component, region, layer or section without departing from the teachings herein.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms, including “at least one,” unless the content clearly indicates otherwise. “Or” means “and/or.” As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. It will be further understood that the terms “comprises” and/or “comprising,” or “includes” and/or “including” when used in this specification, specify the presence of stated features, regions, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, and/or groups thereof.

Furthermore, relative terms, such as “lower” or “bottom” and “upper” or “top,” may be used herein to describe one element's relationship to another element as illustrated in the Figures. It will be understood that relative terms are intended to encompass different orientations of the device in addition to the orientation depicted in the Figures. For example, if the device in one of the figures is turned over, elements described as being on the “lower” side of other elements would then be oriented on “upper” sides of the other elements. The exemplary term “lower,” can therefore, encompasses both an orientation of “lower” and “upper,” depending on the particular orientation of the figure. Similarly, if the device in one of the figures is turned over, elements described as “below” or “beneath” other elements would then be oriented “above” the other elements. The exemplary terms “below” or “beneath” can, therefore, encompass both an orientation of above and below.

“About” or “approximately” as used herein is inclusive of the stated value and means within an acceptable range of deviation for the particular value as determined by one of ordinary skill in the art, considering the measurement in question and the error associated with measurement of the particular quantity (i.e., the limitations of the measurement system). The term such as “about” can mean within one or more standard deviations, or within +30%, 20%, 10%, 5% of the stated value, for example.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

is a perspective view illustrating an embodiment of a droplet inspection apparatus according to the disclosure.is a side view illustrating the droplet inspection apparatus of.

In this specification, a plane may be defined by a first direction DRand a second direction DRcrossing the first direction DR. In an embodiment, the first direction DRand the second direction DRmay be perpendicular to each other, for example. A direction normal to the plane, that is, a thickness direction of an inspection substrate SUB may be a third direction DR. In other words, the third direction DRmay be perpendicular to each of the first direction DRand the second direction DR.

Referring to, a droplet inspection apparatusin an embodiment of the disclosure may include the inspection substrate SUB, a camera CAM, and a receiving portion CTA.

The droplet inspection apparatusin an embodiment of the disclosure may be used to inspect droplets IK discharged from a nozzle portion included in an inkjet head HD.

The inkjet head HD may be included in a printing apparatus for forming an alignment film or applying ultra-violet (“UV”) ink on a substrate in a process of manufacturing a liquid crystal display device, a printing apparatus for applying ink on a substrate in a process of manufacturing an organic light-emitting display device, or the like.

The inkjet head HD may include the nozzle portion capable of discharging the droplets IK, and the nozzle portion may include a plurality of nozzles NZ. The nozzles NZ may be arranged in a line along the first direction DR. Each of the nozzles NZ may discharge the droplets IK.

The droplet IK may be a liquid including various materials. In an embodiment, the droplet IK may be an organic luminescent ink for forming pixels included in a display device, for example. In this case, the organic luminescent ink may be an ink mixed with an organic luminescent material and a solvent. The organic luminescent material may be is a red organic luminescent material, a green organic luminescent material, or a blue organic luminescent material. The organic luminescent material may emit light (e.g., red light, green light, or blue light) when a voltage is applied. The solvent may be a material capable of dissolving the organic luminescent material. The solvent may be a material that is readily miscible with the organic luminescent material.

The droplets IK may include a main droplet MD and a satellite droplet SAT. The main droplet MD may be discharged before the satellite droplet SAT. In addition, the volume of the satellite droplet SAT may be smaller than the volume of the main droplet MD. The discharge amount and the discharge frequency of the satellite droplet SAT may vary depending on the physical properties (e.g., viscosity, surface tension, etc.) of the droplets IK, the temperature of the nozzle NZ, the voltage applied to the inkjet head HD, and the distance between the nozzle NZ and a substrate, etc.

As illustrated in, some of the satellite droplets SAT may not be discharged to a target position due to various reasons (e.g., generation of air current, adsorption of foreign material on the nozzle NZ). In other words, the satellite droplets SAT may include a first satellite droplet SATthat is discharged to the target position along a direction opposite to the third direction DRand a second satellite droplet SATthat is not discharged to the target position. In an embodiment, the droplet inspection apparatusmay inspect for the second satellite droplet SATthat is not discharged to the target position among the droplets IK discharged from the nozzle NZ. In other words, the droplet inspection apparatusmay inspect discharge defects of the satellite droplet SAT of the nozzle NZ.

The inspection substrate SUB may include a transparent or opaque material. In an embodiment, the inspection substrate SUB may include glass or plastic, for example. In this case, the inspection substrate SUB may include a quartz substrate, a synthetic quartz substrate, a calcium fluoride substrate, a fluorine-doped quartz substrate, a soda-lime glass substrate, a non-alkali glass substrate, a polyimide substrate, a polycarbonate substrate, etc. These may be used alone or in any combinations with each other.

The inspection substrate SUB may define a penetrating area which at least some of the droplets IK discharged from the nozzle portion pass. The penetrating area may be disposed on the same line as the nozzle portion in cross-section. In addition, the penetrating area may define a plurality of penetrating holes TH. The penetrating holes TH may correspond to the nozzles NZ, respectively. That is, the penetrating holes TH may be disposed on the same line as the nozzles NZ in the cross-section, respectively. In other words, the penetrating holes TH may be disposed on the same line, that is extending in the third direction DR, as the nozzles NZ, respectively. Accordingly, at least some of the droplets IK discharged from each of the nozzles NZ may pass the inspection substrate SUB through the penetrating hole TH.

In an embodiment, each of the penetrating holes TH may have an elliptical planar shape. However, the disclosure is not limited thereto, and each of the penetrating holes TH may have various planar shapes. In an embodiment, each of the penetrating holes TH may have one of a triangular planar shape, a quadrangular planar shape, e.g., a rectangular planar shape, a circular planar shape, etc., for example.

Specifically, the droplets IK discharged from each of the nozzles NZ to the target position along the direction opposite to the third direction DRmay pass the inspection substrate SUB through the penetrating hole TH. In contrast, a droplet that is not discharged to the target position may not enter the penetrating hole TH. In this case, the droplet that is not discharged to the garget position may be the second satellite droplet SAT. In other words, the second satellite droplet SATmay land on one surface of the inspection substrate SUB without passing through the inspection substrate SUB. As a result, the second satellite droplet SATmay be disposed on the one surface of the inspection substrate SUB without passing through the inspection substrate SUB.

In an embodiment, the inspection substrate SUB may further include a liquid-repellent material. In an embodiment, the liquid-repellent material may include a fluorine-based compound or a siloxane-based compound, for example. The liquid-repellent material may be disposed on a surface of the inspection substrate SUB. In other words, the liquid-repellent material may cover the surface of the inspection substrate SUB. Accordingly, the surface of the inspection substrate SUB may have liquid repellency.